In the combustion of a fuel, such as coal, oil, peat, waste, etc., in a combustion plant, such as a power plant, a hot process gas is generated, such a hot process gas, often referred to as a flue gas, containing, among other components, sulphur dioxide, SO2. The sulphur dioxide is often removed in a so-called wet scrubber, in which the flue gas is brought into contact with a slurry containing, e.g., limestone. The slurry is recirculated from a recirculation tank of the wet scrubber. The sulphur dioxide is absorbed by the slurry, and reacts with the limestone to form calcium sulphite, CaSO3. The calcium sulphite is not a desired end-product, and therefore an oxidation gas containing oxygen is supplied by means of one or several so-called gas spargers to the slurry of the recirculation tank. Typically, the oxidation gas containing oxygen is ambient air, but other gases, such as pure oxygen gas, can also be utilized. The oxygen reacts with the calcium sulphite of the slurry, and converts it to calcium sulphate, CaSO4, i.e., gypsum.
A problem of the known gas spargers is that they tend to become clogged by solid calcium deposits, such as calcium sulphite and calcium sulphate, formed outside and inside of the gas spargers. Such clogging results in frequent maintenance work, which may cause interruptions of the operation of the wet scrubber.